1. Field of the Invention
The present invention relates to a bubble damper of a slurry supply apparatus, and more particularly to a bubble damper of a slurry supply apparatus in which a bubble damper collects bubbles generated by a slurry supply apparatus.
2. Description of the Related Art
In general, a chemical mechanical planarization (CMP) process is a process in which an effect of a mechanical polishing using an abrasive is combined with an effect of a chemical reaction using an acid or basic solution so as to planarize the surface of a wafer.
An abrasive solution used in a CMP apparatus is called as slurry. Fine particles used for the mechanical polishing are uniformly dispersed in the slurry. The slurry is a solution in which an acid or basic solution reacting to a substrate to be abraded is dispersed and mixed in DI water. The slurry is disbursed between a pad and the substrate in the CMP process, and abrades mechanically and chemically the surface of the substrate.
The slurry can be classified into an oxide film CMP slurry and CMP slurry on the basis of the material thereof. Colloidal silica that contains fumed silica dispersed in DI water is commonly used as the oxide film CMP slurry. A solution that contains alumina (Al2O3) particles, ceria (CeO2) particles, or copper (Cu) particle is used as the CMP slurry.
Accordingly, while the particles are mixed in the solution, bubbles may be generated due to characteristic of the solution. Further, while the slurry passes through pipelines, a pump, and valves used to supply slurry, bubbles may be generated due to the vortexes and friction occurring in the slurry.
When the bubbles are generated as described above, the slurry does not have an appropriate compounding ratio in a vessel used to mix the slurry. The reason for this is as follows: Since a sensor cannot accurately detect the amount of slurry containing bubbles, the slurry cannot have an appropriate compounding ratio.
For this reason, there is a demand for a system that suppresses the generation of bubbles in slurry or collects bubbles already generated.